Backplane for flat panel display apparatus, flat panel display apparatus, and method of manufacturing the backplane

ABSTRACT

A backplane includes: a substrate, a pixel electrode, which includes a transparent conductive material, on the substrate, a capacitor first electrode formed on the same layer as the pixel electrode, a first protection layer covering the capacitor first electrode and an upper edge of the pixel electrode, a gate electrode of a thin film transistor (TFT) formed on the first protection layer, a capacitor second electrode formed on the same layer as the gate electrode, a first insulating layer that covers the gate electrode and the capacitor second electrode, a semiconductor layer that is formed on the first insulating layer and includes a transparent conductive material, a second insulating layer covering the semiconductor layer, source and drain electrodes of the TFT that are formed on the second insulating layer, and a third insulating layer that covers the source and drain electrodes and exposes the pixel electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.10-2011-0047944, filed on May 20, 2011, in the Korean IntellectualProperty Office, the disclosure of which is incorporated by referenceherein in its entirety.

BACKGROUND

1. Field

The present disclosure relates to a backplane for a flat panel displayapparatus, a flat panel display apparatus including the same, and amethod of manufacturing the backplane for the flat panel displayapparatus.

2. Description of the Related Technology

Flat panel display apparatuses, including organic light emitting displayapparatuses and liquid crystal display apparatuses, are formed on activetype backplanes that include thin film transistors (TFTs) and capacitorsformed in each pixel to realize high resolution displays.

Oxide semiconductor TFTs are evaluated as optimum devices that can beapplied to backplanes for flat panel display apparatuses since they havehigh performance characteristics and can be processed at a lowtemperature. However, a process for manufacturing backplanes for flatpanel display apparatuses that include oxide semiconductors TFTgenerally includes a plurality of mask processes, thereby increasingmanufacturing costs.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

To address the above and/or other problems, the present disclosureprovides a backplane that may be manufactured in a simple process andhas a high quality display for a flat panel display apparatus, a flatpanel display apparatus including the backplane, and a method ofmanufacturing the backplane.

According to one aspect, there is provided a backplane for a flat paneldisplay apparatus, the backplane including: a substrate, a pixelelectrode that comprises a transparent conductive material on thesubstrate, a capacitor first electrode formed on the same layer as thepixel electrode, a first protection layer covering the capacitor firstelectrode and an upper edge of the pixel electrode and, a gate electrodeof a thin film transistor (TFT) formed on the first protection layer anda capacitor second electrode formed on the same layer as the gateelectrode and using the same material used to form the gate electrode, afirst insulating layer that covers the gate electrode and the capacitorsecond electrode, a semiconductor layer that is formed on the firstinsulating layer and comprises a transparent conductive material, asecond insulating layer covering the semiconductor layer, source anddrain electrodes of the TFT formed on the second insulating layer, wherethe source and drain electrodes are connected to the semiconductor layerthrough the second insulating layer, and at least one of the source anddrain electrodes is connected to the pixel electrode; and a thirdinsulating layer that covers the source and drain electrodes and exposesthe pixel electrode.

The capacitor first electrode may be formed of the same material used toform the pixel electrode.

The transparent conductive material may be at least one selected fromthe group consisting of indium tin oxide (ITO), indium zinc oxide (IZO),zinc oxide (ZnO), indium oxide (In₂O₃), indium gallium oxide (IGO), andaluminum zinc oxide (AZO).

The pixel electrode may further include a semi-transparent metal layer.

The semi-transparent metal layer may include silver Ag.

The first protection layer may be an insulating layer.

The capacitor second electrode may be formed of the same material usedto form the gate electrode.

The semiconductor layer may include at least one metal selected from thegroup consisting of gallium Ga, indium In, zinc Zn, hafnium Hf, and tinSn and oxygen O₂.

One of the source and drain electrodes may be connected to the pixelelectrode through a via hole that simultaneously penetrates through thefirst protection layer, the first insulating layer, and the secondinsulating layer.

The first protection layer, the first insulating layer, and the secondinsulating layer may form an opening that exposes an upper surface ofthe pixel electrode, an etch surface formed by the first protectionlayer and etch surfaces formed by the first insulating layer and thesecond insulating layer may form a gap.

The backplane may further include a second protection layer formed ofthe same material used to form the gate electrode between the firstprotection layer and the first insulating layer, wherein etch surfacesof each of the second protection layer, the first insulating layer, andthe second insulating layer that form an opening are on the same plane.

The first protection layer, the first insulating layer, and the secondinsulating layer may form an opening that exposes an upper surface ofthe pixel electrode, and etch surfaces of each of the first protectionlayer, the first protection layer, the first insulating layer, and thesecond insulating layer that form an opening are on the same plane.

The backplane may further include a second protection layer formed ofthe same material used to form the gate electrode between the firstprotection layer and the first insulating layer, wherein etch surfacesof each of the first protection layer, the second protection layer, thefirst insulating layer, and the second insulating layer that form anopening are on the same plane.

The backplane may further include a capacitor third electrode on thesecond insulating layer.

According to another aspect, there is provided a flat panel displayapparatus including: the backplane described above, a facing electrodethat faces the pixel electrode, and a light emitting unit formed betweenthe pixel electrode and the facing electrode.

The facing electrode may be a reflection electrode that reflects lightemitted from the light emitting unit.

The light emitting unit may include an organic light emitting layer.

According to another aspect, there is provided a method of manufacturinga backplane for a flat panel display apparatus, the method including:forming a pixel electrode and a capacitor first electrode on a substratethrough a first mask process; forming a first protection layer coveringthe pixel electrode and the capacitor first electrode, and forming agate electrode of a TFT and a capacitor second electrode on the firstprotection layer through a second mask process; forming a firstinsulating layer covering the gate electrode and the capacitor secondelectrode, and forming a semiconductor layer that includes a transparentconductive material on a position corresponding to the gate electrodethrough a third mask process; forming a second insulating layer coveringthe semiconductor layer, forming a contact hole that penetrates thesecond insulating layer and exposes a portion of the semiconductorlayer, and forming a via hole that penetrates the first protectionlayer, the first insulating layer, and the second insulating layer andexposes a portion of the pixel electrode through a fourth mask process;forming source and drain electrodes covering the contact hole and thevia hole through a fifth mask process; and forming a third insulatinglayer covering the source and drain electrodes, and forming an openingthat exposes an upper surface of the pixel electrode in the thirdinsulating layer through a sixth mask process.

The pixel electrode and the capacitor first electrode may be formed ofthe same material on the same layer.

The gate electrode of the TFT and the capacitor second electrode may beformed of the same material on the same layer.

The second mask process may further include forming a second protectionlayer having an area smaller than that of the pixel electrode on thefirst protection layer.

The second protection layer may be formed of the same material used toform the gate electrode and the capacitor second electrode.

The fourth mask process may include forming an opening that exposes thesecond protection layer by removing the first insulating layer and thesecond insulating layer, and where the fifth mask process may includeremoving the second protection layer, and the sixth mask process mayinclude removing the first protection layer.

The fourth mask process may include forming an opening that exposes thesecond protection layer by removing the first insulating layer and thesecond insulating layer, and where the fifth mask process may includesimultaneously removing the first insulating layer and the secondinsulating layer.

The fifth mask process may include forming a capacitor third electrodeon the same layer as the source and drain electrodes.

In a backplane according to embodiments of the present invention, a flatpanel display apparatus having the backplane, and a method ofmanufacturing the backplane, the number of masks used is reduced, andaccordingly, manufacturing process can be simplified.

Since a first protection layer is formed on a pixel electrode, damage tothe pixel electrode during a manufacturing process can be prevented.

A capacitance can be increased without increasing an area of capacitorsby forming the capacitors in parallel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages will become more apparent bydescribing in certain embodiments with reference to the attacheddrawings in which:

FIG. 1 is a schematic cross-sectional view of an embodiment of anorganic light emitting display apparatus;

FIGS. 2A through 2F are schematic cross-sectional views showing anembodiment of a method of manufacturing the organic light emittingdisplay apparatus of FIG. 1;

FIG. 3 is a schematic cross-sectional view of another embodiment of anorganic light emitting display apparatus;

FIGS. 4A and 4B are schematic cross-sectional views showing anotherembodiment of a method of manufacturing the organic light emittingdisplay apparatus of FIG. 3;

FIG. 5 is a schematic cross-sectional view of an organic light emittingdisplay apparatus according to a comparative example; and

FIGS. 6A through 6G are schematic cross-sectional views showing a methodof manufacturing the organic light emitting display apparatus of FIG. 5,according to the comparative example.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

Certain embodiments of the present invention will now be described morefully with reference to the accompanying drawings. In the drawings, thethicknesses of layers and regions may be exaggerated for clarity, andlike reference numerals generally refer to like elements.

FIG. 1 is a schematic cross-sectional view of an embodiment of anorganic light emitting display apparatus 1. FIGS. 2A through 2F areschematic cross-sectional views showing an embodiment of a method ofmanufacturing the organic light emitting display apparatus 1 of FIG. 1.

Referring to FIG. 1, in the organic light emitting display apparatus 1,a pixel region PXL1 having a light emitting layer 119, a thin filmtransistor (TFT) region TFT1 having a TFT, and a capacitor region CAP1having a capacitor are formed on a substrate 10.

In the TFT region TFT1, the substrate 10 and a first protection layer 12are formed. In some embodiments, the substrate 10 may be formed of atransparent material, and the first protection layer 12 may be formed ofan insulating film.

A gate electrode 213 of the TFT is formed on the first protection layer12. A first insulating layer 14 that functions as a gate insulating filmis formed on the gate electrode 213, and a semiconductor layer 215 isformed on the first insulating layer 14.

In some embodiments, the semiconductor layer 215 includes a transparentconductive oxide. The transparent oxide may include at least one ofgallium (Ga), indium (In), zinc (Zn), hafnium (Hf), and tin (Sn). Invarious embodiments, the transparent conductive oxide may be one ofInGaZnO, ZnSnO, InZnO, InGaO, ZnO, TiO, and hafnium-indium-zinc oxide(HIZO). An oxide semiconductor TFT that includes a transparentconductive oxide, as an active layer, has high performancecharacteristics and can be manufactured using a low temperature process,and thus, is evaluated as an optimum device for a backplane for a flatpanel display apparatus. The oxide semiconductor TFT has a transparentcharacteristic in a visible light region and is flexible. Therefore, theoxide semiconductor TFT may be applied to a transparent displayapparatus or a flexible display apparatus.

A second insulating layer 16 covering the semiconductor layer 215 isformed. Source and drain electrodes 217 connected to the semiconductorlayer 215 through contact holes C1 that penetrate through the secondinsulating layer 16 are formed on the second insulating layer 16. One ofthe source and drain electrodes 217 is connected to an upper edge of apixel electrode 111 of the pixel region PXL1 via a via hole C2 thatsimultaneously penetrates the first protection layer 12, the firstinsulating layer 14, and the second insulating layer 16.

The pixel electrode 111 that includes a transparent conductive materialis formed on the substrate 10 in the pixel region PXL1. The pixelelectrode 111 may include at least one of indium tin oxide (ITO), indiumzinc oxide (IZO), zinc oxide (ZnO), indium oxide (In2O3), indium galliumoxide (IGO), and aluminum zinc oxide (AZO).

The pixel electrode 111 may be formed as a multiple layer that includesa semi-transparent metal layer 111 a that includes silver (Ag). Asdepicted in FIG. 1, the pixel electrode 111 may further include thesemi-transparent metal layer 111 a that includes silver (Ag) and a layer111 b that includes a transparent conductive material such as ITO on thesemi-transparent metal layer 111 a. The semi-transparent metal layer 111a functions as a semi-transparent mirror and may form a resonancestructure together with a facing electrode 120 that functions as areflection mirror, and thus, can increase optical extraction efficiencyof the display apparatus.

The first protection layer 12 is formed on an upper edge of the pixelelectrode 111. The first protection layer 12 may function as aprotective film for preventing the pixel electrode 111 from degradingduring a manufacturing process of the pixel electrode 111, and mayfunction as a dielectric film of the capacitor. The first protectionlayer 12 may be one of various insulating films formed of a materialselected from SiNx, SiOx, and SiON.

A second protection layer 113 is formed on an upper edge of the pixelelectrode 111 by using the same material used to form the gate electrode213. The first insulating layer 14 and the second insulating layer 16are sequentially stacked on the second protection layer 113. The secondprotection layer 113, the first insulating layer 14, and the secondinsulating layer 16 form an opening for exposing the pixel electrode111. Etching surfaces S1 of the opening in the second protection layer113, the first insulating layer 14, and the second insulating layer 16form the same plane. The second protection layer 113 may function as aprotective film for preventing the pixel electrode 111 from degradingduring the manufacturing process of the pixel electrode 111.

A third insulating layer 18 is formed on the second insulating layer 16,and an opening C4 that exposes the pixel electrode 111 is formed in thethird insulating layer 18. Etching surfaces S2 of the third insulatinglayer 18 and the first protection layer 12 form the same plane.Accordingly, the etching surfaces S2 of the first protection layer 12and the second protection layer 113 that expose the pixel electrode 111may form a gap G.

The light emitting layer 119 is formed on the pixel electrode 111, andlight generated from the light emitting layer 119 is emitted towards thesubstrate 10 through the pixel electrode 111 formed of a transparentconductive material.

The light emitting layer 119 may be formed of a low molecular organicmaterial or a polymer organic material. If the light emitting layer 119is formed of a low molecular organic material, a hole transport layer(HTL), a hole injection Layer (HIL), an electron transport layer (ETL),and an electron injection layer (EIL) may be stacked around the lightemitting layer 119. Also, various layers may be stacked as necessary.The low molecular organic material may include copper phthalocyanine(CuPc), N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), ortris-8-hydroxyquinoline aluminum (Alq3). In embodiments where the lightemitting layer 119 is formed of a polymer organic material, a holetransport layer HTL may be included in addition to the light emittinglayer 119. The HTL may be formed of poly-(2,4)-ethylene-dihydroxythiophene (PEDOT) or polyaniline (PANT). The organic material may be apoly organic material such as poly-phenylenevinylene (PPV), andpolyfluorene.

The facing electrode 120 as a common electrode is formed on the lightemitting layer 119. In some embodiments, the pixel electrode 111 is usedas an anode, and the facing electrode 120 is used as a cathode. Thepolarities of the pixel electrode 111 and the facing electrode 120 maybe reversed in other embodiments.

The facing electrode 120 may be formed as a reflective electrode thatincludes a reflective material. The facing electrode 120 may include atleast one of Al, Mg, Li, Ca, LiF/Ca, and LiF/Al. Since the facingelectrode 120 is a reflective electrode, light generated from the lightemitting layer 119 is reflected by the facing electrode 120 and isemitted towards the substrate 10 through the pixel electrode 111 formedof a transparent conductive material. If the pixel electrode 111 furtherincludes the semi-transparent metal layer 111 a that includes silver Ag,the semi-transparent metal layer 111 a may function as asemi-transparent mirror, may form a resonance structure together withthe facing electrode 120 that functions as a reflection mirror, therebyincreasing optical extraction efficiency of the organic light emittingdisplay apparatus 1.

In the capacitor region CAP 1, a capacitor first electrode 311 and acapacitor second electrode 313 are disposed on the substrate 10 with thefirst protection layer 12 interposed therebetween.

The capacitor first electrode 311 is formed on the same layer as thepixel electrode 111 using the same material used to form the pixelelectrode 111. The capacitor second electrode 313 is formed on the samelayer as the gate electrode 213 using the same material used to form thegate electrode 213. The first protection layer 12 functions as adielectric film. In some embodiments, since the capacitor firstelectrode 311 and the capacitor second electrode 313 are respectivelyformed in the same mask process for forming the pixel electrode 111 andthe gate electrode 213, the manufacturing process may be simplified.

The first insulating layer 14 and the second insulating layer 16 aresequentially stacked on the capacitor second electrode 313, and acapacitor third electrode 317 that is formed on the same layer as thesource and drain electrodes 217. The capacitor 317 may be formed of thesame material used to form the source and drain electrodes 217, and maybe formed on the second insulating layer 16. Since the capacitor firstelectrode 311 and the capacitor second electrode 313 form ametal-insulator-metal (MIM) cap, when the area of the capacitor isincreased to increase a capacitance, an opening ratio of a displayapparatus may be reduced. However, when the capacitor third electrode317 is additionally formed, the capacitance is increased since thecapacitor third electrode 317 is connected in parallel to the capacitorfirst electrode 311 and the capacitor second electrode 313. Therefore,even though the area of the capacitor is reduced, the reducedcapacitance can be compensated for.

The third insulating layer 18, which covers the source and drainelectrodes 217 and the capacitor third electrode 317, is formed and theopening C4 that exposes the pixel electrode 111 is formed in the thirdinsulating layer 18.

Hereinafter, an embodiment of a method of manufacturing the organiclight emitting display apparatus 1 will be described with reference toFIGS. 2A through 2F.

FIGS. 2A through 2F are schematic cross-sectional views showing anembodiment of a method of manufacturing the organic light emittingdisplay apparatus 1 of FIG. 1.

Referring to FIG. 2A, the pixel electrode 111 and the capacitor firstelectrode 311 are simultaneously formed on the substrate 10 in a firstmask process. A buffer layer (not shown) that includes SiO₂ and/or SiNxmay further be formed on the substrate 10 to provide planarity to thesubstrate 10 and to block penetration of foreign elements into thesubstrate 10.

Although the manufacturing process is not shown in detail in FIG. 2A,FIG. 2A shows a result whereby, after depositing a transparentconductive material on the substrate and coating a photoresist (notshown) on the transparent conductive material, the pixel electrode 111and the capacitor first electrode 311 are simultaneously patterned by aphotolithography process using a first mask (not shown). The first maskprocess using photolithography includes a series of processes such asdeveloping, etching, and stripping or ashing after exposing the firstmask (not shown) using an exposure apparatus (not shown). Hereinafter,the same mask processes using photolithography will not be repeatedlydescribed.

FIG. 2B is a cross-sectional view of a result of a second mask processof the embodiment of an organic light emitting display apparatus 1.

The first protection layer 12 is formed on the resultant product of thefirst mask process, and the second protection layer 113, the gateelectrode 213, and the capacitor second electrode 313 are simultaneouslyformed on the first protection layer 12. The second protection layer 113is not formed in a region where the via hole C2 contacts the pixelelectrode 111. Accordingly, the second protection layer 113 has an areasmaller than that of the pixel electrode 111.

FIG. 2C is a cross-sectional view of a resultant product of a third maskprocess of the embodiment of an organic light emitting display apparatus1.

The first insulating layer 14 is formed on the resultant product of thesecond mask process, and the semiconductor layer 215 is formed on thefirst insulating layer 14. The semiconductor layer 215 may include atransparent conductive oxide.

FIG. 2D is a cross-sectional view of a resultant product of a fourthmask process of the embodiment of an organic light emitting displayapparatus 1.

The second insulating layer 16 is formed on the resultant product of thethird mask process, and the contact hole C1 and the via hole C2 areformed. In a region corresponding to the upper side of the pixelelectrode 111, an opening C3 that exposes an upper surface of the secondprotection layer 113 is formed by removing the first insulating layer 14and the second insulating layer 16. Since the second protection layer113 is not removed but remains above the pixel electrode 111, the secondprotection layer 113 protects the first protection layer 12 and thepixel electrode 111 when the contact hole C1, the via hole C2, and theopening C3 are formed.

FIG. 2E is a cross-sectional view of a resultant product of a fifth maskprocess of the embodiment of an organic light emitting display apparatus1.

After depositing a metal material for forming the source and drainelectrodes 217 covering the contact hole C1, the via hole C2, and theopening C3, the source and drain electrodes 217 and the capacitor thirdelectrode 317 are formed by patterning the metal material.

The metal material for forming the source and drain electrodes 217 isalso deposited on the opening C3 that is formed in the fourth maskprocess. The metal material is removed together with the secondprotection layer 113. At this point, if the material for forming thesecond protection layer 113 is the same material used to form the sourceand drain electrodes 217, the second protection layer 113 and the metalmaterial are removed by a single etching process. If the secondprotection layer 113 is formed of a material different from that used toform the source and drain electrodes 217, multiple etching processes maybe performed.

In some embodiments, while the material used to form the source anddrain electrodes 217 is removed from the opening C3 formed on the pixelelectrode 111, the first protection layer 12 protects the pixelelectrode 111.

FIG. 2F is a cross-sectional view of a resultant product of a sixth maskprocess of the embodiment of an organic light emitting display apparatus1.

The third insulating layer 18 is formed on the resultant product of thefifth mask process, and the opening C4 that exposes an upper surface ofthe pixel electrode 111 is formed by removing a portion of the thirdinsulating layer 18. The first protection layer 12 formed on the pixelelectrode 111 is also removed. Accordingly, the third insulating layer18 and the first protection layer 12 may form the same etching surfaceS2.

Another embodiment of an organic light emitting display apparatus 2 willnow be described with reference to FIG. 3.

FIG. 3 is a schematic cross-sectional view of another embodiment of anorganic light emitting display apparatus 2. FIGS. 4A and 4B areschematic cross-sectional views showing an embodiment of a method ofmanufacturing the organic light emitting display apparatus 2 of FIG. 3.Hereinafter, mainly the differences from the organic light emittingdisplay apparatus 1 will be described.

FIGS. 4A and 4B are schematic cross-sectional views respectively showingthe fifth and sixth mask processes of the organic light emitting displayapparatus 2. The first through fourth mask processes of the organiclight emitting display apparatus 2 are performed the same as describedwith reference to the organic light emitting display apparatus 1 of FIG.1.

Referring to FIG. 4A, after depositing a metal material for forming thesource and drain electrodes 217 covering the contact hole C1, the viahole C2, and the opening C3, which are formed in the fourth maskprocess, the source and drain electrodes 217 and the capacitor thirdelectrode 317 are formed by patterning the metal material.

The metal material for forming the source and drain electrodes 217 isalso deposited in the opening C3 in the fourth mask process. The metalmaterial in the opening C3 is removed together with the secondprotection layer 113 and the first protection layer 12. Accordingly,since the second protection layer 113 and the first protection layer 12are etched in the same mask process, the second protection layer 113 andthe first protection layer 12 have the same etching surface S3.

Referring to FIG. 4B, the third insulating layer 18 is formed on theresultant product of the fifth mask process, and the opening C4 thatexposes the upper surface of the pixel electrode 111 is formed byremoving a portion of the third insulating layer 18.

Accordingly, in the organic light emitting display apparatus 2, sincethe first protection layer 12 is removed together with the secondprotection layer 113 in the fifth mask process, the first protectionlayer 12 and the second protection layer 113 have the same etchingsurface S3.

Hereinafter, a comparative example will be described with reference toFIGS. 5 and 6A through 6G. FIG. 5 is a schematic cross-sectional view ofan organic light emitting display apparatus 3 according to a comparativeexample. FIGS. 6A through 6G are schematic cross-sectional views showinga method of manufacturing the comparative example of an organic lightemitting display apparatus 3 of FIG. 5.

FIG. 6A is a schematic cross-sectional view of a result of a first maskprocess of the organic light emitting display apparatus 3. Referring toFIG. 6A, a gate electrode 41 and a capacitor first electrode 51 of a TFTare simultaneously formed on a substrate 40 in the first mask process.

FIG. 6B is a schematic cross-sectional view of a result of a second maskprocess of the organic light emitting display apparatus 3. Referring toFIG. 6B, a first insulating layer 42 is formed on the resultant productof the first mask process, and a semiconductor layer 43 that includes atransparent conductive oxide is formed on the first insulating layer 42.

FIG. 6C is a schematic cross-sectional view of a result of a third maskprocess of the organic light emitting display apparatus 3. Referring toFIG. 6C, a second insulating layer 44 is formed on the resultant productof the second mask process, and contact holes C5 that expose portions ofthe semiconductor layer 43 are formed.

FIG. 6D is a schematic cross-sectional view of a result of a fourth maskprocess of the organic light emitting display apparatus 3. Referring toFIG. 6D, after depositing a material for forming source and drainelectrodes 45 covering the contact holes C5, the source and drainelectrodes 45 are formed by patterning the material. A capacitor thirdelectrode 55 is also simultaneously formed.

FIG. 6E is a schematic cross-sectional view of a result of a fifth maskprocess of the organic light emitting display apparatus 3. Referring toFIG. 6E, a third insulating layer 46 is formed on the resultant productof the fourth mask process, and a via hole C6 that exposes one of thesource and drain electrodes 45 is formed.

FIG. 6F is a schematic cross-sectional view of a result of a sixth maskprocess of the organic light emitting display apparatus 3. Referring toFIG. 6F, after depositing a material for forming a pixel electrode 47covering the via hole C6 formed in the fifth mask process, the pixelelectrode 47 is formed by patterning the material.

FIG. 6G is a schematic cross-sectional view of a result of a seventhmask process of the organic light emitting display apparatus 3.Referring to FIG. 6G, a fourth insulating layer 48 is formed on theresultant product of the sixth mask process, and an opening C7 thatexposes an upper surface of the pixel electrode 47 is formed by removinga portion of the fourth insulating layer 48.

Referring to FIG. 5, a light emitting layer 49 and a facing electrode 50are formed in the opening C7 formed in the seventh mask process.

In the comparative example of the organic light emitting displayapparatus 3, in order to manufacture a backplane that includes a bottomgate type oxide semiconductor, mask processes are performed a total ofseven times. However, in the embodiments of organic light emittingdisplay apparatuses 1 and 2, in order to manufacture a backplane thatincludes a bottom gate type oxide semiconductor, mask processes areperformed a total of five times, including the fifth mask process forforming the pixel electrode 111, or a total of six times, including thesixth mask process for forming the opening C4 that exposes the pixelelectrode 111 by patterning the third insulating layer 18. Accordingly,as a result of the reduction of mask processes, manufacturing costs maybe greatly reduced.

Embodiments of the present invention are described with reference to anorganic light emitting display apparatus, but the present invention isnot limited thereto. The present invention may also be applied to aliquid crystal display apparatus in which a light emitting layerincludes liquid crystals. The present invention may also be applied tovarious kinds of display apparatuses.

While the present invention has been particularly shown and describedwith reference to certain embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

1. A backplane for a flat panel display apparatus, the backplanecomprising: a substrate; a pixel electrode that comprises a transparentconductive material on the substrate; a capacitor first electrode formedon the same layer as the pixel electrode; a first protection layercovering the capacitor first electrode and an upper edge of the pixelelectrode; a gate electrode of a thin film transistor (TFT) formed onthe first protection layer, a capacitor second electrode formed on thesame layer as the gate electrode using the same material used to formthe gate electrode; a first insulating layer that covers the gateelectrode and the capacitor second electrode; a semiconductor layer thatis formed on the first insulating layer and comprises a transparentconductive material; a second insulating layer covering thesemiconductor layer; source and drain electrodes of the TFT formed onthe second insulating layer, wherein the source and drain electrodes areconnected to the semiconductor layer through the second insulatinglayer, and at least one of the source and drain electrodes is connectedto the pixel electrode; and a third insulating layer that covers thesource and drain electrodes and exposes the pixel electrode.
 2. Thebackplane of claim 1, wherein the capacitor first electrode is formed ofthe same material used to form the pixel electrode.
 3. The backplane ofclaim 1, wherein the transparent conductive material is at least oneselected from the group consisting of indium tin oxide (ITO), indiumzinc oxide (IZO), zinc oxide (ZnO), indium oxide (In₂O₃), indium galiumoxide (IGO), and aluminium zinc oxide (AZO).
 4. The backplane of claim1, wherein the pixel electrode further comprises a semi-transparentmetal layer.
 5. The backplane of claim 4, wherein the semi-transparentmetal layer comprises silver (Ag).
 6. The backplane of claim 1, whereinthe first protection layer is an insulating layer.
 7. The backplane ofclaim 1, wherein the capacitor second electrode is formed of the samematerial used to form the gate electrode.
 8. The backplane of claim 1,wherein the semiconductor layer comprises at least one metal selectedfrom the group consisting of gallium Ga, indium In, zinc Zn, hafnium Hf,and tin Sn and oxygen O₂.
 9. The backplane of claim 1, wherein one ofthe source and drain electrodes is connected to the pixel electrodethrough a via hole that simultaneously penetrates through the firstprotection layer, the first insulating layer, and the second insulatinglayer.
 10. The backplane of claim 1, wherein the first protection layer,the first insulating layer, and the second insulating layer form anopening that exposes an upper surface of the pixel electrode, an etchsurface formed by the first protection layer, and etch surfaces formedby the first insulating layer and the second insulating layer form agap.
 11. The backplane of claim 10, further comprising a secondprotection layer formed of the same material used to form the gateelectrode between the first protection layer and the first insulatinglayer, wherein etch surfaces of each of the second protection layer, thefirst insulating layer, and the second insulating layer that form anopening are on the same plane.
 12. The backplane of claim 1, wherein thefirst protection layer, the first insulating layer, and the secondinsulating layer form an opening that exposes an upper surface of thepixel electrode, and etch surfaces of each of the first protectionlayer, the first insulating layer, and the second insulating layer thatform an opening are on the same plane.
 13. The backplane of claim 12,further comprising a second protection layer formed of the same materialused to form the gate electrode between the first protection layer andthe first insulating layer, wherein etch surfaces of each of the firstprotection layer, the second protection layer, the first insulatinglayer, and the second insulating layer that form an opening are on thesame plane.
 14. The backplane of claim 12, further comprising acapacitor third electrode on the second insulating layer.
 15. A flatpanel display apparatus comprising: the backplane of claim 1; a facingelectrode that faces the pixel electrode; and a light emitting unitformed between the pixel electrode and the facing electrode.
 16. Theflat panel display apparatus of claim 15, wherein the facing electrodeis a reflection electrode that reflects light emitted from the lightemitting unit.
 17. The flat panel display apparatus of claim 15, whereinthe light emitting unit comprises an organic light emitting layer.
 18. Amethod of manufacturing a backplane for a flat panel display apparatus,the method comprising: forming a pixel electrode and a capacitor firstelectrode on a substrate through a first mask process; forming a firstprotection layer covering the pixel electrode and the capacitor firstelectrode, and forming a gate electrode of a TFT and a capacitor secondelectrode on the first protection layer through a second mask process;forming a first insulating layer covering the gate electrode and thecapacitor second electrode, and forming a semiconductor layer thatcomprises a transparent conductive material on a position correspondingto the gate electrode through a third mask process; forming a secondinsulating layer covering the semiconductor layer, forming a contacthole that penetrates the second insulating layer and exposes a portionof the semiconductor layer, and forming a via hole that penetrates thefirst protection layer, the first insulating layer, and the secondinsulating layer and exposes a portion of the pixel electrode through afourth mask process; forming source and drain electrodes covering thecontact hole and the via hole through a fifth mask process; and forminga third insulating layer covering the source and drain electrodes, andforming an opening that exposes an upper surface of the pixel electrodein the third insulating layer through a sixth mask process.
 19. Themethod of claim 18, wherein the pixel electrode and the capacitor firstelectrode are formed of the same material on the same layer.
 20. Themethod of claim 18, wherein the gate electrode of the TFT and thecapacitor second electrode are formed of the same material on the samelayer.
 21. The method of claim 18, wherein the second mask processcomprises forming a second protection layer having an area smaller thanthat of the pixel electrode on the first protection layer.
 22. Themethod of claim 21, wherein the second protection layer is formed of thesame material used to form the gate electrode and the capacitor secondelectrode.
 23. The method of claim 21, wherein the fourth mask processcomprises forming an opening that exposes the second protection layer byremoving the first insulating layer and the second insulating layer, andwherein the fifth mask process comprises removing the second protectionlayer, and the sixth mask process comprises removing the firstprotection layer.
 24. The method of claim 21, wherein the fourth maskprocess comprises forming an opening that exposes the second protectionlayer by removing the first insulating layer and the second insulatinglayer, and wherein the fifth mask process comprises simultaneouslyremoving the first insulating layer and the second insulating layer. 25.The method of claim 18, wherein the fifth mask process comprises forminga capacitor third electrode on the same layer as the source and drainelectrodes.